Well so far we have one it's all Bush's fault and one it's all Clinton's falut.
Polyticks aside, the foam didn't work two and a half years ago and one billion dollars later it still doesn't work. Here's an idea. Why not develop a different insulator material. Why not tile the whole main booster.
These things should have been retired a decade ago. It's a shame this country put all it's eggs in one basket and didn't develop a new space vehicle.
At this rate the Chinese are going to pass us up.